Telephony.



E; "31- conwm.

TELEPHONY. APPLICATION FILED JAN 15. 19l5.

. 1,185,374. Patented Mdy30, 1916.

TO OTHER LINKS WITNESSE s I INVENTOR m 1 Q/M I ELMERRCORMN W I ATTORNEY ELMER B. c oRwIN, or crncaeo, ILLINOIS, ASSIGNOR T FRANK :e. COOK comrl iif sr,

or CHICAGO, ILLINOIS, A CORPORATION or ILLINOIS.

I TELEPHONY.

Specification of Letters Patent.

Application filed January 15, 1,815. Serial N0. 2,391. I

To all whom it may concern: Be it known that I, ELMER R. CORWIN,

citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephony, ofswhich the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming apart of this specification.

My invention pertains to telephone, ex-

change systems, one feature of the invention relating particularly to party telephone linesnupon which are party line stations having signal {bells requiring current of differing character or differing ringing circuits whereby any station upon a line may be signaled exclusively of the remaining stations upon-suchjline: ..In practising this feature ofmy-invention-I am able to employ;

a smaller number of ringing current select ing switches for each link connector than there are kinds of'signaling current. These ringing current selector switches are desirably electro-magnetic to enablethe automatic or partial automatic operation thereof, ,though "I do not limit myself to this characteristic. To this end 1 preferably emrespectively responsive to alternating curj rents of fifty cycles, sixteen "cycles andsixtysix cycles. There would then 1 be three sources or means for furnishing such current and, preferably, three operators buttons or keys each for one of such stations and individual to the source of, current adapted to operate such bell. As if have practised the invention for three party line service there are desirably two ringing electro-magnets individual to each link connector of a group of link connectors and so interrelated with each other and with threekeys that these two magnets are enabled to control the application of calling current from the three sources ,toi thel party line (.Ol'i'ilQlI'tGd with the link connector having such magnets for selec- 1.; l

"even though the condensers be absent.

ing current.

tiyzeaty operating the three bells. I There is also desirably employed a master switch for Patented May 30,1916,"

interchangeably associating the three keys with the sources of calling current and the link connectors, this master switch being desirably provided with means whereby it x will normally rest in connection with an idle link connector and will move from association with this link connector when taken for 'use to association witha new idle link connector when the master switch has performed lts portion of the ringing operation In the. preferred embodiment of the invention the master switch seeks a newidle link connector when the ringing current has been initially applied, the control of the ringing current being desirably thereafter automatically effected independently of'the master switch and the ringing buttons. Each link connector is desirably provided with a signal device individual thereto which the master switch operates when it newly comes into association with the link connector having the same so that the operator will know which link connector is next to be newly taken for use.

- Another feature of the invention has for itsobject the provision of means whereby electrically charged lines may be discharged in order that sen'sitive relay mechanism or other telephone equipment that would be effected by a charged condition oflines may be freed of the influence of such charged con-' dition. This feature of my inventionis of particular service in connecting cord circuit or link connector equipment w1th called lines having bell bridges that include condensers therein, though the invention is of se-rviIce n practising the present feature of myiinvem tion I provide means for automatically dischargingthe capacity of the-lines after each period of ringing, for thepurpose stated, and for rendering the signal bells Eltlttl ld stations more sharply to respondto signal- My invention, in another of its aspects, relates to those telephone exchange systems. in which talking battery feed relays are employed for controlling the application of talking battery to connected lincsfmS-uch talking battery relays are usually associated with other relays that open and close the line s,,though the invention is not to be liynited ;.to' the employment of these latter re- Ill) lays. As I have practised the invention these relays are under the control of the master switch which I have provided durs ing the time that the master switch remains in connection with the link connector associated therewith that has been taken for use. After the master switch has performed its function and is moved into association with a new idle link connector these relays are controlled at connected stations and hitherto quickly responded to quick opening and closing of line circuits occasioned, for example, by quick movement of the switch hooks. "The battery feed relays are quick to be energized and released and hitherto the other aforesaid relays were also quick to be energized and released. The condition was such that unintentionally quick vibration of the switch hook at a subscribers station, particularly a called subscribers station, would be followed by such operation of the two relays associated with the line as to remove the talking battery therefrom and break the connection between subscribers. To avoid this condition I make the aforesaid magnets that directly control the continuity of the telephone lines slow to release so that they will not operate when their lines are quickly opened and closed.

The period of release is desirably one sec ond. While this feature of the invention has been employed particularly in connection with battery feed relays I do not wish to be limited tothe peculiar form of line continuity controlling relays to which the invention is applied nor to-the adaptation of the invention to service in connection with two relays coupled with a line.

I will explain my invention more fully by reference to the accompanying drawing showing a single station line and a party station line and telephone exchange equipment for establishing a controlling connection therebetween.

At station 200 I have shown ordinary telephone equipment including a telephone switch-hook 1, a telephone receiver 2, atelephone transmitter'3. a call bell 4, and a condenser 5, the bell and condenser being shown in. permanent bridge while the switch hook is provided. with an upper contact that closes the telephone bridge when the switch is relieved of the associate receiver. The equipment at stations 300, 400 and 500 is desirably similar to equipment at station 200,

similar parts having similar characters of reference. The call/bells 4 4 and i however, which are provided at stations 300, 400 and 500 are not adapted to respond to current of one kind. F or purpose of explanation,it maybe assumed that these bells are respectively responsive to alternating current of fifty 'cycles',,sixteen cycles and sixty-six cycles. Eachof the telephone lines extend to an exchange where it is shown as terminating in the tip and sleeve line springs of a spring jack ,6,'though thefinthis operation by a depression of her listening key 9 to include her telephone set 10 between the answering ends of the tip and sleeve strands of the link connector which she has taken for use. It being assumed that one of the party line stations is to be the called station, the dperator will insert the connecting plug 11. in the jack of the party line having such called station (if the party line has tested free), it being explained that'the operator has taken that link connector'for use whose individual lamp 12 has been caused to glow, by equipment which will later be set forth, to inform the operator that this link connector is nextin order to be taken for use. The operator is provided with three manual keys 13, 14. and 15' (the party line being athree station line) 'which respectively pertain to all bells 4 of the system, all bells 4 of the system, 'and all bells 4 of. the system, and which are respectively individual to sources or means for furnishing alternating current of fifty cycles, sixteen cycles and sixty-six cycles. The'keys 13 and 14 each includes a single grounded contact while key 15 includes two grounded contacts. Each vof these contacts has a complemental contact normally separated therefrom, the complemental contacts of keys 13 and14; being connectedwith wipers 16 and 17 by a master switch while the complemental contacts of keys 15. are respectively connected with these wipers. The wipers 16 and '17 thus constitute elements of a master ringing switch whose sets of waiting contacts are individual to different link connectors, one set of waiting contacts being shown in con nection with the link connector to which it is individual while another 'set of waiting contacts individual to another link connector is not shown in connection with such latter link connector.

i The wipers 1(S and 17 which are shown as resting in connection with waiting contacts individual to the illustrated link connector bring the ringing relays 18 and 19 (there being two such relays individual to each link constitutes a terminal for the ringing source 20, the normal contact of this armature switch constituting a terminal for the ring ing source 21,-while the contact for the upper intermediate armature switch of relay 19 constitutes a terminal for the ringing source 22. The alternate contact of the intermediate armature switch of relay 18 is connected with the lower intermediate armature switch of relay 19 while the normal contact of the former switch is connected with the upper intermediate armature switch of relay 19. The two lowermost armature switches of relays 18 and 19 are connected together and each has as its contact normally separated therefrom the lower terminal of its relay. The upper terminals of the relays are connected together and have a common ground connection through the grounded battery 23 which is preferably 25 'comnion to the exchange but whose illustration is repeated for the sake of clearness of the diagram. If party line station 300 is wanted the operator will depress the key '13 to establish a circuit traceable from the grounded battery 23', the winding of relay 19, thewiper 16 and the waiting contact engaged thereby, the contacts of the depressed key 13, to ground. The relay'19 will thereupon respond to move its armature switches to include the generator 22 (to currentfrom-which the bell 41.1 at station 300 is alone responsive) in a circuit traceable from' ground, through this generator '22,- the ringing timer 2%, intermittently'brought into circuit with said generator, the contact br ush.25 engaging this timer, the then 'engaged contact of the upper intermediate armature switch of relay 19, the normal contact of the intermediate armature switch of relay 18, the normalcontact of the inter-.

mediatearinatureswitch of theringing interrupter relay 26, the sleeve Of the connecting plug 11, the sleeve spring of the jack. 6 of the party line, to all of the bells upon the party line, thence to the tip spring of the jack 601 the party line, the tip of the connecting plug 11, the top armature switch of relay 26, to the ground Ed normal'contact of this switch. The bell 4 at station 300 is the only one which will respond to this current and is therefore selectively operated. If

flirty line station40p-is wanted the operator will depress the key It-to establish a circuit traceable from the grounded battery 23, the

winding of relay 18, the wiper 17 and the waiting contact -engaged thereby, the contacts of the depressed key 14, to ground. The relay 18 will thereupon respond to move its armature switches to include the generator 21. (to current from-whichfthe bell 4 at station 400 is alone responsive) in a circuit traceable from ground, through this generator 21, a ringing timer 27, intermittent-1y brought into circuit with said generator, the contact brush 28 engaging this timer, the then engaged'normal contact of the lower intermediate armature switch of the-now. deenergized relay 19, the alternate contact of the intermediate armature switch of energized relay 18, the normal contact of the intermediate armature switch of the ringing interrupter relay 26, the sleeve of the connecting plug. 11, the sleeve spring of the jack 6 of the party line, to all of the bells upon the party line, thence to the tip spring of-the jack 6 of the party line, the tip of the connecting plug '11, the top armature switch of the relay 26, to the grounded n'ormal contact of this switch; .The bell 4 at station 400 is the only one which will respond tothi-s current and is therefore se lectivelyoperated. If party'lii e station500 i is wanted the operator-will depress the'key 1 15 to establishcircuits for the're1ays18 and. so" going description since one of =the'gcomple--. mental contactsof the key 15 is ingmultiple 19 which will be apparent from the fore:

with the coinplen ental contact fof key'13-- and the other complemental contact of the key 15 is in multiple with the complemental contact of the key 14; The relays 18 and ator 20, the ringing timer 29 intermittently brought into circuit with said generator, the contact brush 30 engaging this timer, the then engagedalternate contact of the lower intermediate armature switch of relay 19', the alternate contact of the intermediate armature switch of relay 18, the normal contact of the intermediate armature switch or" the ringing interrupter relay 26, the sleeve .of the connecting plug 11, the sleeve spring of the jack 6 of the party line, to all of the bells upon the party line, thence to.

thet'ip spring of the jack 6 of the party line, theati-p of the connecting plu'g'll, the'top armature'switch of the relay 26, to the.

grounded normal -contact of this switch. The bell 4 at station 500 is the only one whichwill -respond to this current therefore selectively operated.

It. is desirable to release the actuated button 13, or 14, or 15, after it has initially completed the selectedicurrent to the party line, to which end. means are provided for locking the circuit of the energized magnet 18 or. 19 or the circuits of both when energized. I may employ the calling subscrib.

ers supervisory relay 31 for thispurpose,

the windings of. this relay being bridged across the cord circuit or link connector in and is the usual manner but to which relay an extra armature swltch 31 is added. When this relay is energized the armature switch 31 establishes the locking circuit traceable in part from the grounded battery 23, to the engaged contact of this armature switch by way of the relay wind. or windings v.18, 19 and the lower armature switch or switches ofthese relays and the contacts engaged thereby. Such circuit is completed from the armature switch 31 to the bottom and grounded armature switch of the called battery feed relay 82 by way of the normal contact of this armature switch. The ring ing relay 26 was energized owing to the establishment of circuit traceable from the grounded battery 23, the thimble of the engaged party line jack, the heel of the plug received by the jack, the winding of the ringing relay 26, the intermediate armature switch of the called battery feed relay 32, the.

normal contact of this switch, one or the other or both of the top armature switches of the magnets 18 or 19 according to the energization of these magnet-s, the contacts of such latter armature switch or switches,

the brush 35, the interrupter 36, to ground,

the interrupter 86 being so related to the ringing current synchronously operating in terrupters 24, 27 and 29 as'to establish a circuit for the relay 26 when the selected ringing generator is out of circuit whereby the magnet 26 will be energized only during the time that no calling current is upon the calling line. The circuit for one or the other or both of the magnets .18 and 19 havmg been closed according to the signaling current selected, the master switch having the wipers 16 and 17 is'stepped into association with a new idle link connector, waiting contacts of another link connector being illustrated below the waiting contacts that are engaged by these wipers. This result is due to the establishment of a circuit traceable from the grounded battery '23, the winding of the motor magnet 33, the back contact of the motor armature of the motor magnet, said armature, the wiper 3% of the master switch, the waiting contact with which the wiper 3% is shown in engagement, to the grounded bottom armature switch and its contact of relay 26 when this relay is energized upon the closure of its circuit at The motor magnet 33 will continue in operation until its wiper 34- engages some waiting contact pertaining to some other link connector which is not grounded either at the bottom armature switch of relay 26 of a line being signaled or by way of the intermediate armature switch of supervisory relay 31 (when this relay is energized) and the bottom armature switch of the battery feed relay 32 (when energized), the relays 31 and 32 both being energized when the called party has responded. Re-

of relay 26 and the locking circuit for either or. both of the magnets 18 or 19' is broken at the bottom armature switch of relay 32 whereupon the magnets 18 and 19 are restored to normal. individual to the illustrated link connector, each link connector havingsuch a pair of magnets in similar circuit association, tapsbeing illustrated from the conductors connected with the contacts of the three upper armature switches of the relay 19 which extend to similar contacts of therelays 18 and 19 pertaining to the remaining link 0011- nectors of the group of link connectors to which the master switch is common.

It is desirable to discharge the capacity of the called line after each ringing period, a function which should be accomplished before circuit for the ringing interrupter relay 26 is established at the'interrupter 36 in order that the relay 32 may be free of the impairing effect of the capacity of the called line, this relay therefore being free to operate as it is designed to do. To

this end each ringing generator 20, 21, 22

(or the ringing generator of the system if there be but one) has individual thereto a short, circuiting and grounding device, these devices being illustrated at 37, 38 and 39. lflach short circuiting and grounding device includes a grounded segment and a brush for These magnets are engaging the same, these devices being in the form oi disks which are co-aXial with the disks 2%, 27, 29 and 36 and all of which are mounted upon the shaft of a constantly operating motor 10. But one'circuit interrupting and groundmg device is employed at a time, each according to the source of current which is included in circuit.-

The circuit of the short circuiting and groundingdevice is established just after each ringing period and before the interrupter 36 has broughtthe magnet 26 into circuit, that is before the called subscriber can bring himself llliLOMllQlGPhOlllC communication with the calling subscriber. In

.other'words the order of operation is as fo1- lows: The ringing current is first applied during a ringing period, of about a second, the short circuiting and grounding device is brou ght, into operation immediately upon the conclusion of the ringing period and acts for about one'quarter of a s cond, where after the interrupter 36 is brought into play to energize the magnet 26 during a period of three-quarters of a second during which the called party may bring himself into telephonic connection with the calling party. The discharging connection established by ;,3O Hand will instantly do so when the called line which is employed, thence by oneof the circuits previously traced for the passage of I ringing current, to ground at the upper armature switch of relay 26. Both sides of the called line are thus grounded and consequently short circuited'just after each ringing period and just before the interrupter 36 causes the energization of relay 26'. That is this short circuiting and grounding occursjust before the three-quarter period within which the called subscriber may answer, with the result that the called line is discharged in order that the relay 32 may instantly respond when the called subscriber does answerand may not have opportunity to respond to a discharge of the line capacity a result which frequently occured hitherto at the conclusion of ringing periods. Each period of capacity discharge also preparesthe called line for the proper reception o'fsignaling current to operate the signal bell during the next ringing period.

long.

saidsignal bells; connectors for associziting the signaling circuits with the'party line; sets of electromagnetic switching devices, each set, individual to a connector and each set composed .ofele'ctro-magnetic switching devices-less in number than the differing signaling circuits; circuit connections cooperating with the electromagnetic switchingdevices of each set for enabling them' to establish one signaling circuit and separately to establish other signaling circuits; manual switches equal in number to the signaling circuits and provided with circuit connec tions whereby one manual'switch will operate one electro-magnetic switching device of a set, another manual switch will operate.

another electromagnetic switching device of such-set, and a third manual switch will operate both electro-magnetic switching devices of such set; and a. switch for interchangeably associating said manual switches with the sets. of electro-magnetic switching .devices and the connectors to which they be- 2. A telephone exchange system including telephone lines which are inclusive of a I make the relay 26 slow to release, it r party telephone line extending to a plurality quiring preferably three-quarters ,of a secoi partytelephone line stations having sigond to effect this result. The called battery relay 32 is sensitive to respond and release circuit is opened and closed quickly as, for example, when the switch hook at a called station is flashed. Hitherto the relay 26 would be released so as tobreak the continuity of the telephone connection established at its upper armature switches. By-making the relay 26 slow to release the instantaneous deenergization of relay 32 will have no effect thereupon so that the continuityof the telephonic connection establishedby the relay 26 will not be impaired.

While I have employed the elements 13 to 19 inclusive for eliecting the application of signaling current or signaling circuits to party lines, some of the claims are drawn to cover the use of these elements to whatever operative purpose to which they may be put.

While I-have herein shown and particularly described the preferred embodiment of my iiivention I do not wish to be limited to the precise details of construction and cirtelephone lines which are inclusive of a party telephone lineextending to a plurality nal bells selectively responsive to'difleringf of party telephone line stations having sigr signaling circuits; dilfering signaling cir: cuits for the'selective operation of the"afore" nalbells selectively responsive to differing signaling circuits; differing signaling circuits for the selective operation of the aforesaid signal bells; connectors for associating the signaling circuits with the party line;

sets of electro-inagnetic switching devices,

each set individual to .a connector and each,

set composed v ofelectro-magnetic switching devices. less in number than the difleringsignaling circuits; circuit connections cooperating with the electro-magnetic switching devices of each set for enabling them-to establish one signaling circuit .and separately to establish other signaling circuits;

manual switches equal in number to the signaling circuits-anel'provided with circuit connections whereby one manual switch will; operate one"electro-magnetic switching device of a set, another manual switch will operate another electro-magnetic switching device of such set, and a third: manual 1l5 switch will operate both 'elec'tro-magnetic switching devices of'such set; and a master switch for interchangeably associating said manual switches with the sets of electromagnetic switching devices and the conne'ctors to which they belong-"said master switch being provided with means for elie'cting its association with anunemployed connecto'r'and thereby the association of said manual switches with such. unemployed con.- nector.

1 3. A telephone exchange system including 7 telephone lines which are inclusivev of a party telephone linelextending to a plurality :of p'arty telephone line stations having sigal' bellsselectively responsive to difieriinz signaling circuits; ditiering signaling cirfcuitsfor theselecti've operation of the aforesaid'signal' -bells connectors for associating the-signaling circuits-with the party line;

(connections whereby one manual switch will operate one electroanagnetic switching de vice of a set, another manual switch will operate 'another elect ro-magnetic switching device of such set, and a third manual switch will operate both electro-magnetic switching devices of such set a switch. for-interchangeably associating said manual switches with the sets of electro-magnetic switching devices and the connectors to which they be long; and signal devices individual to the connectors, said switch being provided with v means for effecting the operation of the signal device of the connector with which it comes into association. v,

4. A telephone exchange system including telephone lines which are inclusive of party telephone line extending to a plurality of party telephone line stations having signal; bells selectively responsive .to differing sig-, nalingcircuits; differing signaling circuits" for the selective operation of he aforesaid.

signal bells; connectors for associating the signaling circuits with. the party line; sets switch Wlll operate one electro-magnet of a of electromagnetic switching devices, each set lndividual to a connector and. each set composed of electro magnetic switching devices less in number than the differing, signaling circuits; circult connectlons cotiperating with the electro-magnetic switchingdevices of each set for enabling them to establish one signaling circuit and sepa-' rately to establish other signaling circuits; manual switches equal in number 'to the signaling circuits and provided with circuit connections wherebyone manual switch will operate one electro-magnetic switching de= vice of a set, anothermanual switch will op erate another electro-magnet1c switching device of such set, and a third manual switch will operate both electro-niagnetic switching devices ofsuch set; a mastery tween nector; andsignal devices individual to the connectors, said master switch being provided with means for effecting the operation of the signal device of the connector with which it comes into association.

5. A telephone exchange system including telephone lines; connectors for the telephone lines; sets of electro-magnets for-the con nectors; manuaL-switches provided with cuit connections whereby one 'nianual, switch will operate one electro-magnet of a set," another manual switch will operateanother electro-magnet'. of such set, and a third manual switch will operate both electromagnets of suchset; and a switch for interchangeably associating said manual switches with the sets of electroemagnets.

6. A telephone exchange system including telephone lines; connectors for the telephone lines; sets of electro-magnets for the connectors; manual switches provided with circuit connections whereby one manual switch will operate one electro-magnet of a set, another manual switch will operate an other electro-magnet of such set, and a third manual switch will operate both electromagnets of such set; and a master switch for interchangeably associatingsaid n1an-= 'ual switches with the-sets of electro-magnets; said master switch being provided with means-for effecting its'association with an unemployed connector and thereby the association of said manual s'witcheswith' such unemployed connector.

-'7; A telephone exchange systeml11Clll(l-:

- ingtelephone lines; connectors-tor the tele-' phone lines; sets ofelectro mag nets for the connectors; manual switches provided with circuit connections whereby one" manual set, another manual switch will operate another electro-magnet of such set, and a third manual switch will operate both electro-magnets of such set; a switch for interchangeably associating said manual switches with the sets of electro-magnets; and signal devices individual to the connectors, said. switch being provided with means for etfecting the operation of the signal device of the connector with which it comes into association.

8. A telephone exchange system including telephone lines; connectors for the tele phone lines; sets of electro-magnets for the connectors manual switches provided with 'circuit connections whereby one manual switch will operate one electro-magnet of a I set, another manual switch will operate another. electro-magnet of such set, and third manual switch will operate both electroi magnets of such set a master switch for interchangeably associating said manual switches with'the sets of electro-magncts, said master switch being provided with means for effecting its association with an unemployed connector and thereby the association of said manual switches with such unemployed-connector; and signal devices iirlivi'dualtb fthe connectors, said masterswitch being-provided with means for efecting theoperation of thesignal device of the connector with which it comes into asso:

ciation.

' 1 9. A telephone exchange system includring telephone lines; connectors for -the telephone lines; sets of electro-magnets individual to the connectors manual swltches provided with circuit connections whereby one manual switch will operate one electr omagnet of a set, another manual switch will operate another electro-mag'netof such set,

and a third manual switch will operate both electro-magnets of such set; andaswitch for interchangeably associating saidmanual switches with the sets of electro -magnets.

10. A telephone exchange system includ jing telephone lines; connectors for the telephone lines; sets of electro-magnets ind1' .vidual to the connectors; manual switches provided with circuit connections whereby one manualswitch will operate one electrp- 'magnet of a set, another manual swltch Wlll operate another electro-magnet of such set,

and a third manual switch will operate both electro-magnets of suchgset; and a master switch forinterchangeably associating said manual switches with the sets of electro-magnets, said master switch being provided with .means for efi'ecting its association with an unemployed connector and-thereby the association of said manualswnches with such unemployed connector. I f

11. A telephone exchange system includ- 1 ing telephone lines; connectors for the telephone lines; sets of electro-magnets indi:

vidual to the connectors';"manual switches provided with circuit connections whereby one manual switch will operate one electromagnet of a set, another manual switch will operate another electro-ma'gnet of such set, and a third manual switch will operate both electro-magnets of such set a switch for inter changeably associating said manual switches with the sets of electro-magnets; and signal devices individual to the connecto 5,. said switch being provided with means. "for. ef-

fecting the operation of-thesignal deviceof the connector with which nection. I n

12. A telephone exchange-system including telephone lines; connectors individual to and a third manual switch will operate both electrounagnets ofsuch set; a master switch for interchangeably 'associatlng said manual it comes into con ing telephone lines exten switches with the sets of electromagnets, n

means for efiecting its association with an unemployed connector, and thereby the association of said manual switches with such unemployed connector; and signal devices individual to the connectors, said} master switch being provided with means'fforflefr' footing the operation of. the signal j device of the connector with which it comes into as-. soclation.

13. A telephone exchange system includ-- ing telephone lines extending from substations to an exchange; lin'k connectors at'the exchange for uniting lines in conversation; a common battery for supplying transmitter current to telephone lines; a battery feed relay for intermittently effecting connection "between the lines of unresponding'called parties with link connector equipment; means f r discharging the capacity of the l nes: and means whereby, the capacity 'disv charging means is brought into association said master switch being provided with with a called telephoneline when separated from said link connector equipment.

.14. A telephone exchange system'including-telephone lines extending from substa- 'tionsto an exchange; link connectors at the exchange for uniting lines in conversation; means for intermittently effecting connection between the lines of unresponding called parties with link connector equipment; means for discharging thecapacity of the lines; and automatic means whereby the capacity discharging means is brought into association with :1 called telephone line when separated from said link connector equipment.

i- 15. A telephone exchan e systemincluding from substa* 'tions to an exchange; link connectors at the exchange for uniting lines in conversatiori; a common battery for supplying transmitter current to telephone lines; a battery feed relay for intermittently efi'ecting connection between the lines of 1.1nresponding called parties with link connector equipment; means for discharging the capacity of the lines; and automatic means whereby the capacity discharging means is brought into association with a called telephone line when separated from said link connector equipment.

16. A telephone exchange system including telephone lines extending to an exchange; lmk connectors for uniting lines in conversation and each normally divided into separated sections; a common battery for supplying the telephone lines with transmitter current; battery feed relays "individual to the link connectorsand permanently as-;

sociatedvwith the sections a jacent end sections 'of g'the link connectors; meansv for .dishargingthe. oapaoityiof thelineswhen the 1 n tor r b a e i i i-r l -tliemafter bringing the sections of the link coning telephone lines to discharge their ca-' 7 nectors together. pacity; and means whereby the latter means 15 17. A telephone exchange system includis. brought into association with a called .ing telephone lines extending; to an extelephone line 'upon the conclusion of a ring- 5 change; link connectors for uniting lines in ing period. v o I conversation and each normally divided into In Witness whereof, I hereunto subscribe separated sections; a common battery for my name this eleventh day of January-5 20 supplying the telephone ings wlith tran1s- A; D., 1915. mitter current; attery ec re ays inc ig IT 10 vidual to the link connectors and perma 1 ELMER CORK/Vim nently associated With the sections adjacent Witnesses:

end sections of the link connectors; means G. L. CRAGG,- for grounding both sides and short circuit- ETTA L. WHITE.

Ucpiea of thls patent may be obtained tor five cents each, by addressing the Commissioner oz? v Washington, D. C. 

